1. Field of the Invention
The present invention generally relates to information processing and, more particularly, to an information processing apparatus in which a plurality of processing modules are connected to a ring-shaped bus, an information processing method, and a computer-readable storage medium.
2. Description of the Related Art
Conventionally, there are various methods for controlling bus traffic in an information processing apparatus that uses a plurality of processing modules connected by a ring-shaped bus.
For example, when a variable depth first in first out (FIFO) is arranged on a bus, and output data is output from a processing module, if there is data on the ring (communication unit of the processing module), the two data compete with each other. Therefore, there is discussed a method for, when the competition occurs, deepening the depth of the FIFO to generate empty slots, and preventing the performance of the entire system from significantly deteriorating in Japanese Patent No. 2,522,952.
Also, there is discussed a method in which, for congestion control of a local area network including a plurality of nodes, each node shares network usage status of all the nodes, and a node that wants to start communication determines whether the communication is allowed on the network from the usage status of each node, and then starts communication in Japanese Patent No. 3,034,405.
Here, an information processing apparatus is considered in which a ring type data bus (hereinafter referred to “ring bus”) is formed by stringing a plurality of processing circuits (processing modules) together in a daisy-chain connection by a bus to connect the processing circuits in a ring shape. In a processing apparatus using a ring bus, when data is controlled to circulate only in one direction to simplify the configuration of the processing apparatus, if an amount of data which can be held in each processing module on the ring bus is not taken into consideration, a data collision often occurs, and processing efficiency of the ring bus deteriorates.